Conventionally, when an engine of an automobile and the like is controlled, various sensors such as a cylinder pressure sensor detect various situations such as a combustion state of the engine, and an optimal fuel control and the like is performed based on the detection result. Therefore, it is necessary to accurately detect an abnormal state of the sensor for detecting the state of the engine.
As a failure state of the sensor, there is a failure state called as a so-called stack abnormality in which there is an output range where a sensor value is output properly and the sensor value in a certain output range stays at a constant value. The stack abnormality is different from a simple fixing abnormality. In order to control the engine with high accuracy, it is necessary to accurately detect the stack abnormality. For example, as a technique to detect the abnormality of the cylinder pressure sensor of the engine, there is a technique for determining that the cylinder pressure sensor has the abnormality when an output change (deviation amount) is equal to or less than a predetermined value (for example, refer to Patent Literature 1).